Saudi Coffee image: handleless finjan + brown coffee (Task #396)

Regenerated artifacts/tx-os/public/service-images/saudi-coffee.png
with a sharper prompt that explicitly names a handleless Saudi
finjan (small flared white porcelain cup with a thin gold patterned
rim, no handle) and a clear warm brown coffee color for both the
pour and the liquid in the cup. Strengthened the negative prompt
against handled cups, mugs, amber/orange liquid, and tea so the new
image no longer reads as "tea in a teacup".

Same path as before, so no DB change is needed — the existing
services.image_url ("service-images/saudi-coffee.png") on row id=2
keeps pointing at the new file.

No code, schema, locale, or test changes. Pre-existing `test`
workflow failure is unrelated.

.agents/agent_assets_metadata.toml

@@ -52,7 +52,7 @@ title = "black coffee mug"
 id = "pFSmazHx0m3gsXrCE0oR2"
 uri = "file://artifacts/tx-os/public/service-images/saudi-coffee.png"
 type = "image"
-title = "saudi coffee brown finjan"
+title = "saudi coffee dark brown"
 
 [[outputs]]
 id = "LYgvZ2mSFO2a8Q7YzWuYh"